1. Technical Field
The present invention relates generally to a covering, and more particularly to a transmission mechanism of a window covering, which is capable of efficiently transmitting power to lift the bottom rail and the covering material of the window covering.
2. Description of Related Art
A conventional window covering includes a headrail, a bottom rail, and a covering material between the headrail and the bottom rail. The covering material could be slats, cellular shades, and blanket etc. A typical window covering has at least two lift cords extending out of the headrail, passing through the covering material, and connected to the bottom rail. The lift cords are manipulative to lift and lower the bottom rail and the covering material.
However, when the bottom rail is being lifted, the covering material is stacking up increasingly upon the bottom rail, and it requires more efforts for the user has to lift both the bottom rail and the covering material due to the window covering is getting stacked onto the bottom rail. It is a hard job for the user if it is a big and heavy window covering. Sometime, the user needs to pull the lift cords for several times before the bottom rail is totally lifted.
An early invention of the applicant as taught in U.S. patent publication number 2004/0188038 provides a window covering equipped with a reel in the bottom rail to reduce the power that the user pulls the lift cords. Now, the applicant provides another design.